Home » News » Bubbles, Voids

Bubbles, Voids

Bubbles, Voids
Possible Cause Suggested Remedy
Excessive internal shrinkage a. Increase packing pressure
b. Increase injection forward time
c. Increase gate thickness
d. Minimize, or core out, heavy sections in part design
e. Increase feed, ensure cushion
f. Replace check valve if cushion cannot be held
Melt temperature too high a. Decrease melt temperature
b. Lower back pressure
c. Lower screw RPM
Moisture in material a. Review material handling to eliminate moisture pick up
b. Dry material prior to moulding
c. Utilize hopper dryers
d. Review percent of regrind
Air entrapment a. Add mould venting
b. Relocate gate
c. reduce clamp pressure to allow parting line vents to work
Condensation on mould surface a. Wipe mould surface thoroughly with solvent
b. Increase mould temperature